A proximal segment positioning method to enhance condylar stability after bilateral sagittal split ramus osteotomy in skeletal class II patients: A randomized controlled study.

This study compared condylar stability using two proximal segment positioning methods during bilateral sagittal split ramus osteotom in patients with skeletal Class II malocclusion. 12 patients in the experimental group underwent positioning guided by preoperative mandibular movement trajectory data, a guiding device, and prebent titanium plates, while 13 patients in the control group had manual positioning. Postoperative imaging was performed at 2 weeks (T1), 3 months (T2), and 6 months (T3) to assess condylar and mandibular positions. At T1, both groups showed increased joint space, but the increase in anterior joint space (AJS) was significantly smaller in the experimental group (0.39 ± 0.70 mm) than in the control group (1.10 ± 0.97 mm, P < 0.05). Between T1 and T2, both groups experienced joint space reduction and upward-inward condylar movement, with a less pronounced reduction in AJS in the experimental group (0.28 ± 1.01 mm) compared to the control group (0.98 ± 0.89 mm, P < 0.05). By T3, condylar positions had stabilized, with mandibular relapse significantly lower in the experimental group (12.71 ± 6.43 %) than in the control group (27.09 ± 8.9 %, P < 0.05). These findings suggest that trajectory-guided proximal segment positioning improves postoperative condylar and mandibular stability.